In traditional computer graphics, 3D objects are created using high-level surface representations such as polygonal meshes, NURBS patches, or subdivision surfaces. Because light transport is evaluated only at points on the surface, these methods usually lack the ability to account for light interaction that is taking place in the athmosphere or in the interior of an object.

Contrary to surface rendering, volume rendering describes a wide range of techniques for generating images from 3D scalar data. Volume-rendering techniques are used in